The present invention relates generally to a boring tool, and more particularly to a connection device of the boring tool.
As shown in FIGS. 1 and 2, a prior art boring saw comprises a rotating tool (not shown in the drawings), a rotating body 2, a bit 5, and a connection device 6. The rotating body 2 and the bit 5 are driven by the rotating tool. The connection device 6 is used to connect the rotating tool, the rotating body 2, and the bit 5.
The rotating body 2 is provided with an inner threaded portion 3 and four locating holes 4. The connection device 6 comprises a shaft 7, a locating member 15, and a nut 19. The shaft 7 has a shaft hole 8, a connection portion 9, an urging ring 10 provided with two through holes 11, a first outer threaded portion 12, and a second outer threaded portion 13. The locating member 15 has an annular portion 16 and two insertion pins 17.
In combination, the bit 5 is first inserted into the shaft 7 before the inner threaded portion 3 of the rotating body 2 is engaged with the second outer threaded portion 13 of the shaft 7. The urging ring 10 of the shaft 7 is urged by the rotating body 2. The locating member 15 is fitted over the shaft 7 such that the two insertion pins 17 of the locating member 15 are inserted into the two through holes 11 of the urging ring 10 and the two locating holes 4 of the rotating body 2. The nut 19 is engaged with the first outer threaded portion 12 of the shaft 7 such that the nut 19 urges the locating member 15, which is in an intimate contact with the urging ring 10. The insertion portion 9 of the shaft 7 is finally connected with the rotating tool.
When the locating hole 4 of the rotating body 2 is corresponding in location to the through hole 11 of the urging ring 10 of the shaft 7, so as to facilitate the disposing of the insertion pin 17 of the locating member 15, the rotating body 2 is not necessarily in an intimate contact with the urging ring 15, thereby resulting in formation of a gap which is the culprit for causing the rotating body 2 in motion to sway aside. As a result, the holes bored by such a boring saw have a rough edge. In addition, the rotating body 2 is vulnerable to severance while in operation.
The primary objective of the present invention is to provide a connection device capable of connecting securely a rotating tool with a rotating body of the boring saw.
The connection device of the present invention comprises a shaft, a locating member, a sleeve, and a nut. The shaft comprises a shaft hole to receive a bit, a connection portion for connecting the rotating tool, an urging ring having two through holes, a first outer threaded portion located between the connection portion and the urging ring, and a second threaded portion which is engaged with an inner threaded portion of the rotating body. The locating member comprises an annular portion and two insertion pins. The sleeve is used to fit over the locating member and the urging ring of the shaft. The nut is engaged with the first outer threaded portion for pressing the open end of the sleeve to urge intimately the rotating body.